1. Field of the Invention
The present invention relates to a priming composition comprising (i) at least one silane and (ii) a composition able to form a layer having free OH groups. The priming composition according to the present invention is useful for treating a glass, or part of a glass, so that a resin, such as a polyurethane, upon contact with the treated glass will readily and easily adhere and bond.
The present invention also relates to a process for treating a glass ready to be fitted by bonding in a car body bay or opening with such a priming composition.
2. Description of the Prior Art
The adhesion of a resin, such as a polyurethane, onto the border of a glass permits the glass to be easily bonded into car body bays. The use of resin-bordered glass offers numerous advantages over untreated glass. In particular, when exposed to violent shocks, resin-bordered glass holds in place better. Resin-bordered glass also fits flush against the car body, reducing the penetration coefficient for air into the vehicle.
Resins are commonly bonded to glass by two different methods. The first method consists of bonding the resin directly to the glass or to an enamelled border at the limit of the potted profile of the glass. A second method consists of directly bonding the resin to the potted profile of the glass.
The first method is presently used in the car industry and consists of first depositing on an enamelled surface, at the limit of the potted profile, a precoating incorporating silanes and then subsequently depositing an adhesion primer. An adhesion joint or resin is then bonded to the primer coated glass.
Unfortunately, this procedure suffers from several disadvantages. Firstly, the adhesion primer only remains reactive for a few days. Unfortunately, primer coated glass is typically produced by manufacturers different from those responsible for applying resin to the glass and for subsequently fixing the resin coated glass into car body bays. Typically, the silane precoat and the adhesion primer are deposited on the glass by the glassmaker and the glass is then stored for several days before being installed. After storage, the primer coated glass must be reactivated before resin can be bonded to it. This supplementary step slows the installation of the glass into the body bays. Further, the reactivation step is difficult to automate and result is a loss of productivity on assembly lines.